8" x 2" Mold On Rubber Aluminum Wheel Rigid Caster - 600 lbs. Capacity8" x 2" Mold On Rubber Aluminum Wheel Rigid Caster The mold on rubber aluminum wheel is a lightweight alternative to the traditional cast iron core, providing the same load capacity with a cushioned tread and an attractive look. Tread: Non marking Gray Rubber, Vulcanized to Core Core: Aluminum Bearing: Sealed Precision Ball Bearing Rig: Zinc Plated Rigid Caster, 4 1 2" x 6 1 4" Mounting Plate Capacity: 600 Lbs. Color: Gray and Silver Durometer: Shore